Add project

packages/CefSharp.WinForms.87.1.132/src/CefSharp.WinForms/WebBrowserExtensions.cs

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+// Copyright © 2019 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+using System;
+
+namespace CefSharp.WinForms
+{
+    /// <summary>
+    /// Helper extensions for performing common CefSharp related WinForms tasks
+    /// </summary>
+    public static class WebBrowserExtensions
+    {
+        [System.Runtime.InteropServices.DllImport("user32.dll")]
+        private static extern bool DestroyWindow(IntPtr hWnd);
+
+        /// <summary>
+        /// Manually call https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-destroywindow
+        /// passing in the handle returned from <see cref="IBrowserHost.GetWindowHandle"/>.
+        /// This method can be used to manually close the underlying CefBrowser instance.
+        /// This will avoid the WM_Close message that CEF sends by default to the top level window.
+        /// (Which closes your application). This method should generally only be used in the WinForms version.
+        /// </summary>
+        /// <param name="chromiumWebBrowser">the ChromiumWebBrowser instance</param>
+        /// <returns>If the function succeeds, the return value is true.</returns>
+        /// <example>
+        /// <code>
+        /// //Invoke on the CEF UI Thread
+        /// Cef.UIThreadTaskFactory.StartNew(() =>
+        /// {
+        ///   var closed = chromiumWebBrowser.DestroyWindow();
+        /// });
+        /// </code>
+        /// </example>
+        public static bool DestroyWindow(this IWebBrowser chromiumWebBrowser)
+        {
+            if (!Cef.CurrentlyOnThread(CefThreadIds.TID_UI))
+            {
+                throw new InvalidOperationException("This method can only be called on the CEF UI thread." +
+                    "Use Cef.UIThreadTaskFactory to marshal your call onto the CEF UI Thread.");
+            }
+
+            if (chromiumWebBrowser.IsDisposed)
+            {
+                return false;
+            }
+
+            var browser = chromiumWebBrowser.GetBrowser();
+
+            if (browser == null)
+            {
+                return false;
+            }
+
+            var handle = browser.GetHost().GetWindowHandle();
+
+
+            return DestroyWindow(handle);
+        }
+    }
+}